People in coastal regions of Asia, particularly those living in cities, could face some of the worst effects of global warming, climate experts will warn this week. Hundreds of millions of people are likely to lose their homes as flooding, famine and rising sea levels sweep the region, one of the most vulnerable on Earth to the impact of global warming, the UN states.

The report – Climate Change 2014: Impacts, Adaptation and Vulnerability – makes it clear that for the first half of this century countries such as the UK will avoid the worst impacts of climate change, triggered by rising carbon dioxide levels in the atmosphere. By contrast, people living in developing countries in low latitudes, particularly those along the coast of Asia, will suffer the most, especially those living in crowded cities.

A final draft of the report, seen by the Observer, will be debated by a panel of scientists set up by the Intergovernmental Panel on Climate Change (IPCC) this week at a meeting in Yokohama, Japan, and will form a key part of the IPCC's fifth assessment report on global warming, whose other sections will be published later this year.

According to the scientists who have written the draft report, hundreds of millions of people will be affected by coastal flooding and land loss as global temperatures rise, ice caps melt and sea levels rise. "The majority of it will be in east, south-east and south Asia. Some small island states are expected to face very high impacts."